The manufacture of a window frame, among other steps, includes the cutting and assembly of extruded frame or sash profiles with the appropriate glazing material to build an assembled window. The assembled window frame provides structural protection to the glazing for handling and transportation and provides the structure for the frame to be used in the construction process. During manufacture, the window frame may be provided with a variety of profiles and grooves to enhance the aesthetic appeal of the window frame.
Recent developments in window manufacturing have seen an increase in the use of plastic window frames, such as polyvinylchloride (PVC) or acrylic, for the frame and/or sash of the window. Typically, a vinyl window frame is assembled by cutting an extruded frame or sash profile to appropriate lengths and heat welding the cut profiles together around the perimeter of the glazing. The heat welding process adds plastic material to the weld joints (weld bead) which detracts from the aesthetic appeal of the window and may interfere with the conformity in size of separate assembled units. For example, it is necessary that the sash of window fits within the frame. Accordingly, it is necessary to remove the excess weld material from around the weld joints to provide a smooth joint. The removal of weld material from the outside surface of the window frame is called corner cleaning. Removal of weld material from the upper and lower surfaces of the window frame in combination with grooving the window frame joint is called shadow grooving. Shadow grooving is desirable to provide decorative enhancement of the joint and mask extrusion tolerances from batch to batch.
As window frames are manufactured and assembled in a series of manufacturing steps, it is desirable to have a machine that is efficient in the corner cleaning and shadow grooving steps of the manufacturing process. Specifically, a machine is required that enables rapid and accurate damping of welded units to be cleaned and rapid and accurate removal of the excess weld material in order to reduce the time spent on the cleaning step of manufacture. A machine is also required that enables shadow grooving to be performed at the same time during the manufacturing process.
As well, it is desirable to provide a corner cleaning machine that enables rapid exchange of the cutting elements of the machine (cutter block) for cleaning different frame profiles. Rapid exchange of cutting elements reduces the set-up time of the machine which improves overall manufacturing efficiency.
There has also been a need for a machine with almost exclusively pneumatic logic controls in order to simplify operation of the machine, thereby reducing the manufacturing time and costs associated with window frame manufacture. Specifically, there has been a need for a machine where the clamping, cutting and shadow grooving operations are under pneumatic control. There has also been a need for a machine that enables the exchange of cutter blocks by pneumatic control.
In the past, there has also been a need for a machine where the movement of the cutting elements is through an arc to produce a smoother corner in order to provide a single pass method of removing excess weld material from the window frame corner.
There has also been a need for a machine with an effective clamping system for holding the work piece that ensures correct work piece alignment without the use of additional limit switches or holding devices.
In the past, single-spindle, single-position machines that have been developed to remove the excess weld material have been slow to operate and have required time consuming operations to both remove the excess weld material and to change cutters for cleaning different frame profiles.
Other machinery companies have developed a corner cleaning machine that removes the weld bead by a back and forth or side to side motion of the cutter block. Furthermore, these machine require the use of tools to exchange cutter blocks for different profiles.